Additional Basics on Remote Control
R&S
®
NGL200
138
User Manual 1178.8736.02 ─ 02.01
A.3.1
Structure of a SCPI Status Register
Each standard SCPI register consists of 2 or 3 parts (Event, Condition and Enable reg-
ister). Each part has a width of 16 bits and has different functions. The individual bits
are independent of each other, i.e. each hardware status is assigned a bit number
which is valid for all 2 or 3 parts. Bit 15 (the most significant bit) is set to zero for all
parts. Thus the controller can process contents of the register parts as positive inte-
gers.
A
STATus:QUEStionable:INSTrument:ISUMmary1
exists as often as device
channels are available (e.g. NGL201 = 2 channels = 2 status register). Accordingly, the
description text of the channel information changes in
channel 1, instrument 2 = channel 2 etc.).
Depending on the value of the read register, you can draw conclusions on the current
status of the device. For example, when the unit operates in constant voltage, the
result of the returned ISUM register is a decimal "2" which corresponds the binary
value of "0000000000000010".
Any part of a status register system can be read by query commands. A decimal value
is returned and represents the bit pattern of the requested register. Each SCPI register
is 16 bits wide and has various functions. The individual bits are independent, i.e. each
hardware status is assigned to a bit number.
Bits 9 to 12 are still "free" resp. unused (always return a "0"). Certain areas of the reg-
isters are not used. The SCPI standard defines only the "basic functions". Some devi-
ces offer an advanced functionality.
Each channel of the power supply is considered as separate "instrument" (SCPI stan-
dard definition). Therefore, e.g. the register "Status: Questionable: Instrument: Isu-
mary" of the NGL202 is also present two times (Isummary1-2).
Description of the status register parts
The SCPI standard provides two different status registers:
Status Reporting System
